The correlation between the microstructure and the magnetization switching field of individual Co/Pt multilayer nanodots with Pt or Ta/Pt underlayers has been investigated by transmission electron microscopy and magnetic force microscopy. The insertion of a 2-nm-thick Ta underlayer promoted the Co/Pt  crystal axis orientation and improved the mean switching field and the switching field distribution of nanodot arrays with a diameter of 70nm from 1.4 to 6.9 kOe and from 22 to 8%, respectively. Electron microscopy of individual dots has revealed that all the nanodots without the Ta layer contain (200)-oriented grains, which possibly work as nucleation sites owing to a small perpendicular magnetic anisotropy. However, no structural difference is found among the dots having the same underlayers, suggesting the existence of other factors affecting the switching field distribution.
ASJC Scopus subject areas
- Physics and Astronomy(all)